Effects of cryoanalgesia on post-thoracotomy pain

The present study was conducted to determine the efficacy of cryoanalgesia and its complications in patients with post-thoracotomy pain, operated in Masih-Daneshvari hospital in 2001-2.

Sixty patients entered this clinical trial. After thoracotomy, patients were equally distributed in two groups of control and cryoanalgesia. Nerve freezing was carried out for 60 seconds at a temperature of -60 degrees Celsius. Pain was measured by Visual Analogue Scale. Meanwhile, patient's demand for pethidine was recorded till the 7th day. Sensory complications were surveyed through telephone call till the 3rd postoperative month. Pain score, sensory complications and the amount of pethidine administration were compared between the groups.

The mean age (SD) of control and "Cryo" patients were 41.315 and 41.916 years, respectively. In the recovery room, pain score of 2-3 was reported in 63.3% of control subjects, the remaining 36.7% had experienced pain score of 4-5. These figures were 86.7% and 13.3% for the "Cryo" group, respectively (p<0.05). During the following days, pain score was significantly higher in the control subjects. At the 7th day, however, pain score of 0-1 and 2-3 were reported in 13.3 and 86.7% of the control subjects, whereas these figures were 83.3 and 16.7% for the "Cryo" subjects, respectively (p<0.00001). During the first day, pethidine was administered 151.627 mg and 87.548 mg for the control and "Cryo" subjects, respectively (p<0.001). Hypoalgesia, reported in 93.3% of the patients at the end of the first week, disappeared by the end of the 3rd month. Allodynia and dysesthesia was reported in 10% of the subjects at the end of the first week and vanished by the second month.

Cryoanalgesia could safely diminish post thoracotomy pain also, it may eliminate the need for opiates. It has few complications that are soon relieved. We strongly recommend this technique and complementary research in this field.